1. Technical Field
The present disclosure relates to methods for making the carbon nanotube structures, particularly, to a method for making the twisted carbon nanotube wire.
2. Description of Related Art
Carbon nanotubes are tubules of carbon generally having a diameter of 0.5 to 100 nanometers, and composed of a number of coaxial cylinders of graphite sheets. Carbon nanotubes have interesting and potentially useful thermal, electrical and mechanical properties, and have recently attracted a great deal of attention for use in different applications such as field emitters, gas storage and separation, chemical sensors, and high strength composites.
However, the main obstacle to actual application of carbon nanotubes is their difficulty to process due to the powder form of the carbon nanotube products. Therefore, forming separate and tiny carbon nanotubes into manipulable carbon nanotube structures is necessary.
Recently, as disclosed by patent application US20080170982 to Zhang et al., a twisted carbon nanotube wire has been fabricated. As shown in FIG. 2 of US20080170982, a carbon nanotube structure is drawn from a carbon nanotube array and directly twisted at the same time to form a twisted carbon nanotube wire. During twisting of the carbon nanotube structure, more and more carbon nanotubes are drawn from the carbon nanotube array, and a twisted carbon nanotube wire is formed and extended.
However, in the drawing and twisting process, the twisted carbon nanotube wire is joined with the carbon nanotube array, such that the carbon nanotube array can provide relatively weak pulling force (i.e., the van der Waals attractive force between adjacent carbon nanotubes). Therefore, the achieved twisted carbon nanotube wire may have clearances between adjacent carbon nanotubes due to the curve of the carbon nanotubes formed, and the density and tensile strength of the twisted carbon nanotube wire are relatively small.
What is needed, therefore, is to provide a twisted carbon nanotube wire having relatively high density and tensile strength and method for making the same.